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Unformatted text preview: CEE 3770  Summer 2009 Practice Test 1 June 4, 2009 (12:00 p.m.  1:45 p.m.) Do not read any page other than this instruction sheet before the official start time. Be sure to write your name on EVERY page! Please use the space provided to answer your questions. Use the back of each page if you need extra room. Do not attach any extra sheets. Exam is closed book. You are not allowed to use notes or textbooks. You are allowed to use a calculator, but you may not share it with anyone else. Please refer to the last page for the standard normal distribution table. 1 Name: 1. (18 points) Jake, Alan, Charlie, and Rose are taking CEE 3770. They go to the library once a week to do their homework. Assume that each student shows up at random and acts independently of each other. (a) As if she has nothing better to do, the instructor observes the students in the library for a week. What is the probability that she cannot find any of the students over the weekend? Solution: The probability that a student doesnt go to the library over the weekend is 5/7. Then, the prob. that none of them shows up is (5 / 7) 4 = 0 . 260 (b) What is the probability that she sees the students on all different days? i.e. all students visit the library on different days. Solution: This is almost same as Birthday problem. 7 days have equal probabilities that a student will show up. Pr (4 students go to the library on all different days) = 7 6 5 4 7 4 = 0 . 350 (c) As if she still has nothing better to do, she observes the students for two weeks. Assume that students go to the library every week. What is the probability that she sees the students on all different days for those two weeks?...
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This note was uploaded on 06/29/2009 for the course CEE 3770 taught by Professor Staff during the Spring '08 term at Georgia Institute of Technology.
 Spring '08
 Staff

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